Dear Steven,
The linearized stiffness matrix of the mooring system for the ITI Energy barge is documented in my Oct 11, 2016 post in the following forum topic: Generate new mode shapes for the 5MW ITIBarge4 wind turbine - #7 by Xin.Tong.
I’m not aware of any publication where the linearized stiffness matrix of the mooring/tendon system for the MIT/NREL TLP is documented. However, the MAP++ model for this system is available in the FAST archive (see file NRELOffshrBsline5MW_MIT_NREL_TLP_MAP.dat). While I have not use the Python wrapper for MAP++, my understanding from the online documentation is that this wrapper can be used to derive the linearized stiffness matrix: map-plus-plus.readthedocs.io/en/ … ample.html.
An RAO is a linear effect, and so, should be independent of the sea state. But the approach used to derive the RAO (including the sea state conditions) is documented in that Section - i.e. regular waves of different frequencies with a wave height of 2 meters. Since that report was published, we now recommend deriving RAOs using irregular white-noise wave excitation, as documented in the following publication: nrel.gov/docs/fy13osti/58098.pdf.
Best regards,